Thermoplastics advantages

Repair possibilities a significant thermoplastic advantage for large parts... 

Unsaturated resias based on 1,4-cyclohexanedimethanol are useful ia gel coats and ia laminating and molding resias where advantage is taken of the properties of very low water absorption and resistance to boiling water (6). Thermal stabiHty is imparted to molding resias, both thermoplastic (71,72) and thermoset (73—76), enabling retention of physical and electrical properties at elevated temperatures (77). Additionally, resistance to chemical and environmental exposure is characteristic of products made from these resias (78). 

Thermoplastic resins produced from pure monomers such as styrene, alkyl-substituted styrenes, and isobutylene are produced commercially. An advantage of these resins is the fact that they are typically lighter in color than Gardner 1 (water-white) without being hydrogenated. Among the earliest resins in this category were those made from styrene and sold as Piccolastic. Styrene and alkyl-substituted styrenes such as a-methylstyrene are very reactive toward Friedel-Crafts polymerization catalysts. 

Improved heat resistance is the most important advantage of cross-linked polyethylene (XITK) over thermoplastic polyethylene. A power cable... 

Thermosetting-encapsulation compounds, based on epoxy resins (qv) or, in some niche appHcations, organosiHcon polymers, are widely used to encase electronic devices. Polyurethanes, polyimides, and polyesters are used to encase modules and hybrids intended for use under low temperature, low humidity conditions. Modified polyimides have the advantages of thermal and moisture stabiHty, low coefficients of thermal expansion, and high material purity. Thermoplastics are rarely used for PEMs, because they are low in purity, requHe unacceptably high temperature and pressure processing conditions. 

Advantages of the electron beam processor are its abiUty to penetrate thick and highly pigmented coatings. It is used to cross-link reactive unsaturated polymers, nonreactive thermoplastic polymers, iasulation, and wire-cable covetings (4,9,16) (see Insulation, electric-wire and cable COVERDIGS). 

Injection-Molded Products. Numerous housings, electrical enclosures, and cabinets are injection-molded from rigid PVC. These take advantage of PVC s outstanding UL flammabiUty ratings and easy mol ding into thin-waHed parts. PVC has developed melt flow capabiUties to the point where it competes with essentially any other flame-retarded engineering thermoplastic and molds easier than most. 

Thermoplastic polyesters achieved some commercial success during the mid-1980s however, these were eventually replaced by nylon coating powders in functional coatings and thermosetting polyester powders in decorative appHcations because of lack of any unique characteristics or price advantages (see Polyesters, thermoplastic). 

The physical properties of block copolymer TPE also depend on the type and arrangement of the blocks. Table 5 compares the property advantages of various block copolymer thermoplastic elastomers. 

Thermoplastic elastomers have now been available for over 30 years and the writer recalls organising a conference on these materials in 1969. In spite of considerable publicity since that time these materials still only comprise about 5-10% of the rubber market (equivalent to about 1-2% of total plastics consumption). It is important to appreciate that simply being a thermoplastic material (and hence being processed and reprocessed like a thermoplastic plastics material) is not enough to ensure widespread application. Crucially the material must have acceptable properties for a potential end-use and at a finished product price advantageous over other materials. 

Advantages The major advantages of the thermoplastic-based disposal systems are by dispiosin of the waste in a dry condition, the overall volume of the waste is greatly reduced most thermoplastic matrix materials are resistant to attack by aqueous solutions microbial degradation is minimal most matrices adhere well to incorporated materials, therefore, the final product has good strength and materials embedded in a thermoplastic matrix can be reclaimed if needed. 

When the material is allowed to cool it solidifies again. This cycle of softening by heat and solidifying on cooling can be repeated more or less indefinitely and is a major advantage in that it is the basis of most processing methods for these materials. It does have its drawbacks, however, because it means that the properties of thermoplastics are heat sensitive. A useful analogy which is often used to describe these materials is that, like candle wax, they can be repeatedly softened by heat and will solidify when cooled. 

---